Abstract
Secondary dento-alveolar disharmonies, resulting from partial edentations and periodontal disease of upper frontal teeth, are often accompanied by issues of existing space. The complex clinical and paraclinical examination and assessment underlines the changes in the parameters describing the contour and chromatics of the remaining teeth and the parameters of the potential prosthetic spaces.
The elaboration of an illustrative schema that combines these values is welcome during the conception of the treatment plan.
The individualised conceptual interpretation of the „law of the face” and „light and shadow”, associated with the visual tolerance of the patient, will allow the practitioner and the dental technician to adequately make all the aesthetic restorations.
The cosmeticisation through the use of therapeutic procedures that create optical illusions, accompanied by the interactive instruction of the patients and the evaluation of their satisfaction, resulted in a high therapeutic effectiveness.
Keywords: dento-gingival composition, optical illusion, aesthetic restauration
Introduction:
The description of the morphological features of frontal teeth is of great importance, because it provides us with “basic geometrical rules” that allow us to shape the structures typical of each tooth. Teeth are generally defined by their bidimensional contour, which can be easily assessed. However, in order to fully characterise a tooth, one must not overlook several other aspects: texture, colour, shape and contour. [1, 6]
L. Williams suggested a classification of dental shapes based on the correlation between the contour of the face and that of the superior central incisor. It can be applied arbitrarily, without there being some sort of generalisation in this regard. Nevertheless, the aesthetic effect of placing the teeth in harmony with the varied design of the lips prevails in the dento-facial composition. From a morphopsychological standpoint, it has a major impact on the aesthetics of the lower face. [3]
Following this idea, J.P. Frush and other authors have suggested to instil various aspects of an individual’s personality into the dental structures, allowing for a more precise characterisation of the dental composition. The existing balance between the facial regions must be assessed in accordance with the quantitative and qualitative values of the elements of the facial, dento-facial and dento-gingival compositions. [1, 4]
According to C. Rufenacht, the upper lip expresses intellectual sensibility, the lower lip- sensuality. Their fullness and length reflects the influence of some morphopsychological traits rooted in heredity. Obtaining a balance between the positioning of frontal teeth and the conformation of the lips will significantly increase the harmony of the dental and dento-facial compositions and will underline the individual’s personality traits. In scientific literature, there are numerous methodologies to assess the design of the lips along with guides of aesthetic reconstruction based on certain studies that aim to individualise the dento-facial composition. [1 ,6, 7]
When talking about the dento-gingival composition, the type of gingival smile denotes in a more critical aspect the perception of harmony of dental and periodontal components. [1, 6]
Various authors have suggested numerical correlations between the shape of the teeth and other facial landmarks. Based on the quantification of dental dimensions, we have got the principle of proportions, also known as the “harmony of proportions”, which enjoys a systematic employment in the procedures of dental reconstructions/restorations. The biometric studies around this subject are inconclusive, and the assessment of numerical correlations relies on “aesthetic intuition”, derived from years of constant and conscious training in assessing proportions. [2, 6, 7]
While further analysing the aspect of the superficial texture of teeth, one should mention that an exact reproduction of this aesthetic effect should deliver a result similar to natural teeth. The optical assessment of the light reflected by the superficial texture of the enamel reveals an indicator based on the subjectivity of visual perception. As stated by certain authors, the structure of an object influences its optical properties, and respectively- the ratio of absorbed, reflected and refracted radiation. [1, 5, 6]
We see most objects because of the light they reflect. Certain physical, physiological and psychological aspects of light, comprised in the theories of Young and Herring, explain the sensation of apparition, creation and perception of colours. [1]
There are multiple visual systems for comparing and describing the colour of teeth. However, the Munsell system, based on hue, chroma and value is the one that is unanimously accepted by clinicians. Chroma is determined by the ratio between the spectral and white colour. In the context of the behaviour of dental structures under light radiation, colour saturation is mainly dictated by dentine, but influenced by the thickness and transparency of the enamel. The optical effect of luminance/value is mainly determined by the quality and thickness of the enamel. [3, 6]
Knowing these particularities of dental chromatics helps us in complex clinical situations, when through control over the reflection of light and the colour contrast, one creates optical illusions. Interactively employing the concepts of “The Law of The Face” and “principle of illumination” that comprise the aspects described above, allows the clinician to harmonise the dento-gingival and dento-facial compositions.
Purpose of the research
The assessment of the dento-gingival composition of upper frontal teeth in secondary dento-alveolar disharmonies and the elaboration of a clinico-therapeutic algorithm of cosmeticisation of the overall aesthetic aspect.
Materials and methods
15 subjects (10 men, 5 women), aged between 28 and 52 years, with secondary dento-alveolar disharmonies, resulting from partial edentations and periodontal disease of the frontal teeth, underwent a complex clinical examination and assessment.
The analysis of diagnostic casts allowed us to determine the dimensions of the teeth adjacent to the edentulous spaces and the parameters of the potential prosthetic space, and compare them within the dento-gingival composition. The photographic method was employed to document the curative and diagnostic steps of the case. Imaging methods were used to assess the quality of endodontic treatment, the presence or absence of caries, the degree of periodontal damage and the visualisation of the transition lines of the interproximal areas that border the apparent vestibular face. The resulting data was written down in the dental records of the patients. Their analysis enabled us to elaborate the clinico-therapeutic algorithm of individual cosmeticisation of the aesthetic aspect. The assessment of the colour properties of the teeth was carried out through the visual method, using the Vitapan 3D Master (VITA) and Esthet-X colour guides. The data was recorded in the chromatic guide-schema for upper frontal teeth designed by the authors. The psychological aspect of the patients was assessed through medical dialogue and the WHO-5 questionnaire [8] (Fig. 1.).
Analysis and interpretation of results
In order to interpret the application of the aesthetic principle of the dento-facial composition in the subjects included in the study, we have initially compared the shape, texture and contour of the resting upper front teeth to the schematic illustrations of the concepts proposed by Frush and Fisher, Rufenacht, Williams and Hulsey. This allowed us to analyse certain aspects of correlation between the shape of upper front teeth and the design of the face, the lips and the dental shape pattern specific to each subject. [1, 4, 6, 7]
The values of the parameters of the bidimensional contour of upper frontal teeth was analysed using the golden ratio 0.618:1:1.618 and the harmonious height-width ratio of 1:0.8, while admitting a variation of ± 0.2. The dimensional parameters of the potential prosthetic space were estimated, depending on the position of the missing tooth, in comparison to the remaining symmetrical tooth (Fig. 2.).
A – the dimensions of the „real” vestibular face;
B – the demarcation of proximal enamel.
The objectives of this parametrisation consisted in the elaboration of a bidemensional design between the length and width of the teeth within the individual dento-gingival composition of the subjects on the radiographic images. The proposed quantification method allowed demarcating the „apparent” vestibular face from the „real” dental contour with the help of transition lines traced schematically (Fig. 3.).
A – the dimensions of the „real” vestibular face,
B – the demarcation of proximal enamel,
C – the limits of the „apparent” vestibular face,
D – the transition areas
Consequently, the dimensional nonconformities of the frontal dental compositions were identified, followed by the selection of adequate principles of creation of optical illusions: shortening, elongation, narrowing, widening.
The cosmeticisation was carried out through the following procedures:
- The accentuation of vertical lines and convexities
- Long and straight incisal edges
- Incisal edges with cervical inclination in the distal zone
- Wide embrasures and narrow mesiodistal incisal edges
- The oral inclination of the incisal zone
- The reduction of the central prominence
- Flattening the vestibular surface
- Increasing the curvature of the central prominence
- Adjusting the lateral prominences
- The proximal displacement of prominences
- Artificial gum
Along with the assessment of the chromatic characteristics of chroma and value through the visual method, the colour contrast was manipulated through the following procedures:
- Cervical colourations
- Interproximal pigmentation
- The luminance of the gingival third
- The creation of linear angles
- Interproximal luminance
- Manipulating the hue saturation through layering.
The evaluation of the visual tolerance of the subjects was carried out in similar illumination, taking into account the following factors: tiredness, age, food habits, the administration of certain medications, pathological aspects.
Following the fine chromatic assessment, we have specified the value and chroma of the hue with the help of the Vitapan 3D Master (Vita) colour guide, in a standardised environment, respecting the basic rules described in scientific literature. The data was registered in the chromatic guide-schema designed by the authors for planning the therapeutic procedures of cosmeticisation of the upper front teeth and the succession of their application. Following this, the patients were interactively demonstrated and explained the therapeutic possibilities of colour manipulation, in order for the subjects to be aware of the limitations of the treatment options.
In this context, the psychological profile of the subjects was taken into consideration, in order to assess the predictability of their attitude towards the proposed therapeutic solution.
The feedback data concerning the individual visual tolerance was written down in their dental records. This approach, mostly subjective in nature, along with the dental procedures from the described clinico-therapeutic algorithm, proved its effectiveness in the questionnaire described in the suggested methodology, yielding better results.
Conclusions
- The clinico-paraclinical evaluation of quantitative and qualitative parameters of dento-gingival compositions was at the basis of elaborating our individual schemas for the aesthetic treatment plan.
- The systematic employment of the principles of comseticisation, along with informing and instructing the subjects, proved its effectiveness through the results of the questioning carried out in this study.
Bibliography
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